Axial flow compressor and like machines



Oct. 19, 1948. J. s, HA| 2,451,944

- l AXIAL FLow COMPRESSOR ANDy LIKE MACHINES Filed Jan. 125, 1944 2 Sheets-Sheet 1 Oct. 19, 1948. 4 J. s. HALL 2,45l,944

AXIAL FLOW COMPRESSOR AND LIKE MACHINES Filed Jan. 13, 1944 2 Sheets-Sheet 2 Parental oei. 1e, 194s AXIAL FLow coMPnEsson AND LIKE MACHIN Joseph Stanley Hall, Sale, England, assignor to Metropolitan-Vickers Electrical Company `Lim-- lted, London, England, a company of Great Britain Application January 13, 1944, Serial No. 518,181

In Great Britain January 21, 1942 section 1, Public Law 69o, August s, 194s Patent expires January 21. 1962 i 1s' claims. (c1. 23o-123i This invention relates specically to axial flow compressor or turbine type machines, or sections of machines, of the kind having a plurality of consecutive intercalated rows or stages of mutually co-operating relatively rotating substantially radial blading carried by two generally cylindrical members arranged one within the other and of dliIerent diameters to provide between them an annual passage along which the elastic or inelastic iiuid, acted vupon by the blading therein or acting upon it, is progressively impelled or compressed or expanded (or decompressed) so that, at least in the case of elastic iluid, the sectional area of said passage may, and usually will, change progressively along its length. i One of blading is 'arranged as an outer or inner tier, and

l the remainder in one or more successive coaxial `or composite elements so formed may be allowed to rotate, or remain stationary, as desired.

such blade-carrying cylindrical members may be stationary, in which case it is more conveniently,

but not necessarily, the inner one which rotates,

the bladingcarried by the outer member then constituting guide blading. Alternately the two blade-carrying members may rotate in opposite directions providing a contra-rotational arrange'- ment. The two generally cylindrical blade-carrying members will be hereinafter for convenience called rotors, and contra-rotational arrangements only of air compressors will be conn sidered in detail, but it is to be understood that the invention includes within its scope arrangements wherein either rotor may be fixed.

The present invention is applicable in general to any axial ilow machine as above specified dealing with any uid and to the following machines in particular by way of example, namely high pressure and exhaust turbines for steam or gas; air, vapour or gas compressors, superchargers, fans; and even liquid pumps or turbines; and it is appli-cable to combinations of such apparatus.

The invention, however, is notably concerned with the high efficiency, high speed air compressors of internal combustion or gas turbine plants primarily for the propulsion of aircraft or other craft. I

It will be appreciated that by reason of the high speed of rotation of the rotors and'of the high duty of the rotary members of gas turbine plant every part thereof must be accurately and rigidly located, with the rotors truly coaxial and i accurately balanced. In arrangements wherein the outer rotor is rotating it is desirable that it should rotate at the highest practicable speed, so` that this rotor cannot be constructed in halves, that is, split on a diametrical plane, for the purpose of enabling it to be assembled, in the well known manner, around the finished inner rotor. However, the invention has advantages in arrangements wherein the outer rotor is split and need not rotate.

Particularly when the gas turbine plant is for the propulsion of aircraft, where the weight of and the volumetric space occupied by the plant must be reduced to reasonable minima, the carrying out of the construction of the plant has presented, and still presents, many problems, particularly regarding the compressors or like ma- The invention is also applicable to combinal chines with which the present invention is more particularly but not exclusively concerned. There may be mentioned by way of example the problems of mechanical strength, rigidity, reliability, ease and rapidity of assembly and faciiit-y for mass production, as well as the provision and location of the ball or other bearings oi the rotating members and the driving connections thereof.

In the case more particularly of the multi-stage air compressors or like machines .a very important problem is a construction enabling the bladecarrying rotors to be assembled. In this respect two different general methods and arrangements have inter alia been described in the specifications of prior U. S. applications Serial Nos. 518,167 and 518,168 illd of even date herewith, now abandoned, both arrangements involving the construction of the consecutive blading rows or stages on separate foundation members which are consecutively assembled in line, with the provision of spacing rings or distance members and keying and/or other torque transmitting means so that thc intercalated rows of blading of each group are built up consecutively into respective oppositely or relatively rotating rotors In the specication of said U. S. application Serial No. 518,168 the compressor blading of each row, except the end rows, is carried in or on the centre part of a foundation ring which integrally constitutes also the spacing ring, the rings being slid into and on to outer and inner continuous relatively thin-walled cylinders alternately, to constitute the two rotors. In the specification of said U. S. application Serial No. 518,167 the two multi-stage rotor cylinders of a turbine driving a compressor are themselves progressively built up together of aligned cylindrical sections which may be bolted together and/or riveted and/or welded together one after the other, there being in this case no continuous cylindersreceiving foundation rings.

In either case it is, in some arrangements of the plant, necessary to drive the outer rotor from one or both of its ends. In general there are several torque-transmitting circumferential joints in the rotor, whilst special apparatus is necessary for ensuring that the two rotors which become interlocked together on assembly shall be truly concentric and accurately balanced.

The present invention comprises the manufacture of a machine of the kind specified, wherein each of the relatively rotating rotors, or sections thereof, areY individually fully bladed and assembled, the one separate from the other, with at least two of the relatively rotating rows or stages of blading having such form and pitch :that they can be mutually -interthreaded, then assembling together the thus .bladed rotors involving the movement of the one into the other in the mainly axial direction. 1

Since it is in many cases necessary or desirable for the outer rotor to have bearing means at each end the construction in this case involves that there must be some, and in general there need be no more ythan one, ycircumferential joint in the outer rotor, and that the blading in each of the stages or rows which pass through one another in the process of mutually inserting in an axial direction one rotor into the other not only has the same number of blades but the blades have such appropriate form and pitch that the blades of these rows can be passed between one another. With the arrangement according to the invention it is, of course, not possible to have shrouding of the type which is xed to the blade tips, but this, in fact, is not required since the rotor cylinders themselves ycan in general form Ithe boundary surface of the fluid passage. Those rows of blades which pass each other during the assembly must also either be in line or have uniform angular advance when viewed along the axis of the machine, and for this reason it is convenient to mount the blades in continuous rectilinear or spiral grooves in the rotors such as in accordance with British application No. 5,942 of 1941. Where the blades in both rotors are of the same section the clear spaces between the blades must be at least equal to half a pitch on any diameter.

rows of blading. However, the circumferential `joint need not be at one end of the outer rotor. It

may in fact be anywhere between the ends of the rotor ywhereby it `becomes possible to incorporate blades of two further different forms and pitches along the length of the compressor. This will be appreciated from the fact that if the circumferential join-t is, say, near the middle of the outer rotor then the two parts can be separately assembled around the inner rotor from opposite ends thereof so that fewer rows of blading have to pass between one another during the longitudinal shifting of said two parts into position.

It is to be appreciated that the actual shape of the air passage through the compressor in longitudinal section may be considerably varied. Either rotor cylinder providing the boundary wall of the air passage, or either portion of the divided one, may be truly cylindrical, and the other one of truly conical or of flaring shape, or both or all may be conical or flaring. however, have to be met. Thus when the circumferential `joint is so located that in the process of in'tercalating the blades of the inner and outer rotors the blade row or rows on both portions of the divided rotor pass blades on the undivided rotor in bringing together the two divided portions, then considering the cylindrical, conical or shaped surfaces from which the blades project, namely outwardly from the inner and inwardly from the outer surface, and considering the variation in diameter of each of these two surfaces of revolution as the transverse plane under consideration moves from that of the joint towards the end of the compressor in either direction, the requirement to be met is that on neither rotor may this surface increase in diameter from the joint towards the end, up to the position of the last row of blades which has been passed by a row on 'the other rotor. When the circumferential joint is located so 'that to the one side of it the blade rows of the two rotors do not have to pass one another axially during the assemblyproc'ess the restrictions on diameter apply to the structure Vin the direction of the other portion only. It is on these considerations andthe required Iheights of blading that the shape of the passage is determined.

It is to be understood that the circumferential joint above referred to is of such design and proportions that it can be made and broken without aecting the accuracy of the balance of the rotor. The rotors are completely bladed, assembled and balanced. The outer one is then divided and threaded on to the inner, and the joint remade. Nothing has been done to affect the balance of the inaccessible inner rotor, and if any adjustments are required to the outer rotor, they are simple and readily made.

It will be also appreciated that since there is only one such circumferential joint the size of the iianges or scantlings required for providing the Joint need not involve a material increase in the weight of the compressor. Actually there is no objection to the provision of further circumferential joints of a permanent nature, since these can be made lof smaller dimensions such as by the employment of rivets or welding. The provision of such further joints need not introduce any structural difficulty, because the rotors can be balanced andl adjusted independently after the joints have been permanently made.

It will be understood that where the circumferential joint is located at either end of the outer rotor the latter then comprises a main portion Certain conditions,

Y lvention the aforesaid feature of interthreading is applied to constructions of axial flow machines with single or multiple blading tiers, at least one ofthe rotors of which is connected at one end only to its'driving shaft or the shaft which it drives, such as by substantially radial or conical discs, sometimes through annular swan-neck members which give flexibility. In such case there need be no non-permanent circumferential joint in any rotor, though there may be and usually will be permanent joints, that is joints which are required for the construction of the individual rotors or stators, but which thereafter remain permanently jointed-up, and playno part in the assembly or dismantling of the machine.

The laccompanying drawings illustrate someat the right-hand end of the rotor members I and 2'can be assumed to be connected to driving members 22 and 24, which may be, for example, sleeve vsha1-ts carried by appropriate bearings (not shown), the members 2l and 24 being shown fragmentarily in dotted lines. It will be understood, however, that the rotor members I and 2 may be carried at their right-hand ends on additional bearings similar to the bearings 20 and 2I what diagrammatically in conventional form (except Figures 2 and 3), the upper halves in sectional elevation, several contra-rotational arrangements of machines according to the invention:

Figure 1 showing a typical simple arrangement;

Figure 2 is an end elevation, and

Figure 3 a sectional plan view illustrating the form and pitch of blading appropriate for the interthreading thereof,

Figures 4 to 9 show modifications of the arrangement shown in Figure 1, and

Figs. 10 to 14 show typical multi-tier arrangements. l

In Fig. 1 is represented a contra-rotational air compressor or supercharger, the annular passage of which has its walls formed, as an example, by the outer hollow cylinder member I and the inner slightly conical cylinder member 2, the direction oi' air flow being indicated by the arrows. In the example thereV are in all eleven rows or stages of blading, I to XI, of which the odd-numbered stages are carried by the outer rotor cylinder I and the even-numbered stages by the inner rotor cylinder 2.

In the arrangement shown in Fig. 1, as in all the other illustrated arrangements, it may be assumed for convenience that the blades are provided wlth individual roots of dovetail or equivalent form lheld in longitudinal or helical grooves of corresponding dovetail or like form in the members I and 2, as indicated by the dotted lines 3. The blades of the stages II to X inclusive have respective inner and outer roots only, the blade tips beingunshrouded and being sufficiently adjacent the inner and outer walls of the rotorl members I and 2. The blading of stages I to XI, however, has substantially radially inner foundation rings I2 and I3 respectively which are connected to or integral with discs or wheels Il and I5. The innerrotor member 2 has attached to it or integral with it at its left-hand end a disc member I6 and at its right-hand end a disc member I1. At I8 is shown a stationary member constitutingjthe inner wall of the annular air inlet to the compressor, this member being supported in any convenient manner and being integral with -or connected to a disc member I9 which carries the ou-ter races of ball bearings 20 and 2|. The

inner race of the ball bearing 20 is carried by a provided. for the left-hand end of members.

At the right-hand end of the rotor cylinder member I is a flange 25 secured by bolts or screws (not shown) to a flange`26 on an outer ring 21 in grooves in which radially outer roots of the these rotor -blades of the stage I are engaged.

ing the inter-threading of the blading of the i stages IV, VI, VIII and X of the inner rotor between the blading of the stages IlI, V, VII and IX ofthe outer rotor. After this part of the process of assembly the disc I5 carrying theyblading stage XI and rings I3 and 21 is flttedinto position and the flanges 25 and 26 bolted together, the'bearings being also assembled. ciated that, as hereinbefore set forth, the blading of stages I and XI will not have undergone interthreading,.so that these stagesmay have al different design and pitch from those of stages III to X, which must conform to the requirement permitting the inter-threading' as illustrated by way of'example by Figs. 2 and 3, which need no description beyond stating that the arrow 28' indicates that the space as viewed in the axial direction between the consecutive blades, such as VI and VIa in one row carried by the inner rotor member 2, must be not less than half-pitch to permit the blading VII, for example, carried by the outer rotor member I to pass between the blades VI and VIa..

The arrangement shown in Fig. 4 di'ers only from'the arrangement shown in Fig. l in that it is the inner rotor cylinder 2a which is truly cylindrical, whilst itis the outer rotor cylinder la. which is conical. It will be appreciated that the actual surfaces of members such as I and 2, la` and 2a may be curvilinear to provide the necessary "flaring by which the progressive change inthe sectional shape of the annular air passage is obtained. The joint 25, 26 is at the left-hand end of the rotor cylinders Ia, 2a.

As shown in Fig. 5 both rotor cylinder members may be corneal in the same sense, and ob. viously they may be both conical in opposite,

senses.

In the arrangement illustrated by Fig. 6, furthermore, the disconnectable joint between flanges 25a and 26a is nearly in the centre of the length of the rotor members Ic and Id, and 2d, whereby the greater flexibility as regards changes of blade design from stage to stage can be achieved all as hereinbefore set forth. It will be noticed in Fig. 6 that the outer rotor part Ic is truly cylindrical as is also the right-hand end, beyond the flange joint, of the inner rotor member 2d, whilst the conicitles of the member I'd and the left-hand part of the member 2d are It will be appre- 7 of' opposite sense. But it will be appreciated, as hereinbeiore set forth, that considerable latitude in these respects is permissible, within limits.

In Fig. 7 is shown an arrangement generally similar to that shown in Fig. 6, except that the inner rotor member also is formed in two sections 2e and 2f having flanges 29 and 30 respectively which can be non-permanently secured togather (but which must be secured before assembly), 'whereby even greater flexibility is permissible in the design of the blading along the stages as governed by the limitations hereinbefore set.

Fig. 8 shows an arrangement which in principle differs only from the arrangements shown in the preceding figures in the respects that, rst, the end ring 21a is riveted (or may be welded) at 2lb to the left-hand end of the outer cylinder I g, whilst, secondly, the respective driving shafts 23a and 24a of the rotors ig, 21a and 2g are in axial alignment.

The arrangement shown in Fig. 9 diiIers from that shown in Fig. -8 in that the outer rotor la, 21a is carried on a shaft 23h whilst the inner rotor 2g is carried on a sleeve shaft 2lb, between which and the shaft 23h are the bearings 3l. At the left-hand end of the machine is a fixed structure 32 which may be connected through radial webs or fixed guide blading 33 with a ilxed casing 3l enclosing the rotational parts of the machine, whilst at the right-hand end of the latter is a stationary structure 35 which may be similarly connected by radial webs or fixed guide blading 36 with a member 31 non-permanently jointed at flanges 38 with the right-hand end of the casing 34. Between a sleeve portion of the stationary structure 35 and the sleeve bearing 2lb are bearings 39, whilst a bearing 40 is pro- .vided between a sleeve portion of the member 32 and the left-hand end of the shaft 2lb.

In the arrangement shown in Fig. 10 there are two tiers of multi-stage blading, the blading of theinner tier A being contra-rotational and conveniently turbine blading. having the two contra-rotational rotor cylinders 4I and I2, the inner rotor 4i of which isfixed to a power shaft I3 extending axially from the machine, whilst the other rotor member l2 of this turbine is combined with, and thus drives, the rotational blading of the outer tier B, which may be that of a compressor or supercharger or .similar machine. having alternate rows of outer blading projecting radially inwards from a stationary outer casing It will be appreciated that the rotor cylinder 42 thus has blading projecting radially outwards as well as blading projecting radially inwards. Said rotor 42 may have its left-hand en d row of inner blading provided with a foundation ring I connected through a "swan-neck l or other flexible member 46 to a disc 41 rigid with a shaft 48 mounted in ball bearings 49 carried in a stationary sleeve 50, which may be in turn carried by a ilxed disc or'diaphragm 5I connected through the inner and outer tiersy of blading at the extreme left-hand end oi' the machine to the casing 44. Similarlyl the shaft 43 may be mounted in bearings 52 carried in a stationary sleeve 53 connected through a disc 5I supported through the inner and outer tiers of ixed guide blading or radial webs with the member 55 bolted by ilanges to the right-hand end of the casing M.

The arrangement shown in Fig. 11 diners, in

`neck member 46c, to the shaft 48.

the mam, from that shown in Fig. 1o in that the blading of both the inner and outer tiers A and B are contra-rotational and the two rotors are locatedin a xed outer casing 56, associated with which at each end of the machine are double tiers of iixed guide blading by which the two aligned shafts are carried through their bearings generally in the manner described with reference to Fig. 10. The machine necessarily has three rotors 4|, I2 and 44. 'I'he latter is drivingly connected with the inner most rotor through a row of double tier rotor blading at the right-hand end of the machine and through an additional swan-neck or other flexible. member 48a.

In the contra-rotational arrangement shown in Fig. 12 there are two intermediate rotor cylinders 42a and 42h between the inner and outermost blading tiers A and B. The outermost rotor a is connected through the extreme left-hand end blading row of the outer tier B, through the swan-neck member 4Gb and left-hand blading row of the inner part of the machine and swan- 'I'he rotor member 2b is connected at its right-hand end through a swan-neck member 45d through the right-hand row of inner tier blading to the innermost rotorl member 4| and to the shaft 43. The two rotor cylinders 42a and 42h may be separated merely by a clearance space. A stationary casing may be provided for the machine, if required, such as shown in Fig. 11 and as described with refer. ence thereto.

It will be appreciated that the feature oi.' the concomitant inter-threading of the blading of the rotors into their operative positions is generally applicable to arrangements involving one, two, three or more tiers of blading and so connected that they form one, but preferably two or more, separate rotors. Each tier of blading may have two or more rows or stages. 0n the other hand in the case of double tierarrangements such as shown in Figs. 13 and 14, inter-threadingv may be involved in the inner tier blades, whilst mere juxtaposition of the outer tier blading rows is required. such as when there are only two such,

rows, which are indicated at IIa and IIb in Figs. 13 and 14, which may be ducted fan stages driven by an exhaust or power turbine in accordance with U. S. application Serial No. 518,167. In Figs. 13

and 14 the inner tier turbine is shown as havingv only four stages of blading I, II, III and IV, of which it is only necessary that the inner stages II and III of blading shall be arranged for intervthreading. Apart from this the genral structure of the arrangement shown in Figs. 13 and 14 of the drawings accompanying the present speciiication will' be generally understood after a :perusal of the specication of the U. S. application just above mentioned.

With regard to Figs. 8 to 14, the shape of the fluid passage in longitudinal section is only limited by the restriction concerning tapering rotor drum diameters and by the consideration that in the process of assembly complete rings cannot pass blades which occupy the same annular space. These considerations are in ,the main similar to those applying in the arrangements shown in Figs. 1 to 7 above described. For instance, considering the shape of the fluid passage in longitudinal section, taking any particular annular passage space and assuming that in separating two rotor members the outer boundary of that space is to be moved to the right relatively to the inner one, then the condition to be met is that neither of the two boundary cylindrical or conical or flaring surfaces may decrease in. diameter from right to left: or vice versa if, in separating, the outer boundary is moved to the left. It will be appreciated that in spite of this restriction freedom is left to make the cross-section of the annular space tapering in either direction as desired.

'It is to be understood that the rotor cylinder members, or section-s thereof, instead of being continuous integral parts as illustratedin the accompanying drawings, may in either or each rotor be previously built up of blade row sub-sections permanently circumferentially` jointed together by rivets or bolts or welds.

I claim:

l. The method of manufacturing a machine of the character specified which includes the steps of assembling a fully bladed member, separately assembling the sections of a second fully bladed member with each section provided with at least one row of blading having such form and pitch that it can be interthreaded with at least one row of blading on said iirst member, moving the sections of said second member axially toward one another and telescopically with respect to said first member into operative relationship while interthreading the blading of said rows on said sections with rows of blading on said first member, and vjoining adjacent ends of said sections and thereby maintaining the latter in assembled relationship on said first member.

2. Apparatus of the character described comprising an annular fully bladed member, a second annular fully bladed member divided axially into sections, each of said sections comprising at least one row of blading of such form and pitch that it can be interthreaded with at least one row of blading on said first member, a blade ring additional to at least one of said members, and means for connectingadjacent ends of said sections -to maintain the latter in assembled relationship on said iirst member. f

3. Apparatus of the character specified comprising contra-rotational members one within the other and carrying rows of radial blading, internal bearings for rotatably supporting said members, and a blade ring additional to at least one of said members, the blading of said members being of such form and pitch that they may-be interthreaded for assembly.

4. Apparatus of the character speciiied comprising relatively rotatable inner and outer members carrying rows of radial blading, at least one of said members being divided axially into sections at least one of which is conical, and having means for securing them together by a circumferential joint, the blading of said members.

being of such form 4and pitch that they may be interthreaded.

5. Apparatus of the character specified comprising relatively rotatable inner and outer bladed members, at least one of said members being divided axially into sections having means for consections h'aving means for connecting them by a circumferential joint between the ends oi' said l passage, at least one of said sections having a conical boundary wall for said passage, the blading of said members being of such form and pitch -that the blading of the sections composing one member may be interthreaded with the blading on the other member by axial movements of said sections toward one another.

7. Apparatus of the character specified comprising relatively rotatable inner and outer members carrying radial blading and spaced apart to form a passage between them which converges toat said joint, the blading o1' said members being of such form and pitch that the blading of the sections composing one member may be interthreaded with the blading of the other member by axial movements of said sections toward one another.

8. Apparatus of the character specified comprising relatively rotatable inner and outer bladed members having walls spaced apart radially to form a converging passage between them, at least one of-said members being divided axially into sections having means for connecting them by a circumferential Joint between th'e ends of said passage, a wall of one member defining said passage at one side of said Joint and a wall of the other member defining said passage 'at the opposite side of said joint being cylindrical and the walls of said members opposite to the respective cylindrical walls being conical, and the blading of said members being of heights conforming with the shape of said passage and being of such shape and pitch that the blading of the sections com'- posing one member may be interthreaded with the blading of the other member by axial movements of said sections toward .one another,

9. Apparatus of the character specied comprising inner and outer relatively rotatable bladed members spaced apart radially to form a passage between them, each of said members being divided axially into sections having means for 'formi118 a circumferential joint between their 'adjacent ends, the boundary wall of said passage on one section of each' member being conical and said wall on the other section of the respective member being cylindrical, and the blading of said members being of such shape and pitch that the inlA blading of the sections of one member may be interthreaded with the blading of the sections of the other member.

10. Apparatus of th'e character specified comprising inner and outer radially spaced relatively rotatable bladed members at least one of which is divided axially into sections, means for forming a circumferential joint to connect the adjacent ends of said sections, the blading of said members being of such shape and pitch that the blading of the sections of one member may be interthreaded with the blading of the other member by axial movements of said sections toward one another `and telescopically with' respect to said other member, and rings carrying additional blading and having means for securing them to the outer ends of said sections.

11. Apparatus of the character specifled comprising inner and outer radially spaced relatively rotatable bladed members at least one of which is divided axially into sections, means for ccnnecting adjacent ends of said sections to form a circumferential `joint between them, the blading of said members being of such shape and pitch that the blading of th'e sections of one member may be interthreaded with the blading of the other member by axial movements of said sections toward one another and telescopically with respect to said other member, and supporting'elements for said sections carrying additional blading and having means for securing them to the outer ends of the respective sections.

12. Apparatus oi the character speciiled comprising inner and outer radially spaced relatively rotatable bladed members each' divided axially into sections having means for connecting their adjacent ends .to form a circumferential Joint, and means including blade rings carried by one of said members toward its respective ends for rotatably supporting it, the blading of said members being of such shape and pitch that the blading of the sections oi one member may be interthreaded with the blading of the sections of the other member.

13. Apparatus of the ch'aracter specied comprising contrarotational members one `within the other and spaced apart radially to form a Passage between them, and carrying rows of blading disposed in said passage, the boundary wall of said passage on at least one of said members being conical, internal bearings for rotatably supporting said members, and a blade ring additional to at least one of said members, the blading or said members being of such form and pitch that they maybe interthreaded for assembly.

14. Apparatus of the characterspeciiled comprising relatively rotatable inner and outer members spaced apart radially to iorm a passage between them and carrying tiers of radial blading disposed respectively in said passage and radially outwardly from said members, and a blade ring additional to the tier of blading of at least one of said members, th'e blading of said members .disposed in said passage being of such form and pitch that they may be interthreaded for assem- 15. Apparatus as deilned in claim 14, wherein the boundary. wall of said passage-on one of said members is conical.

16. Apparatus of the character specified ccmprislngYV relatively rotatable members one within the other and spaced apart radially to form a passage between them, and carrying rows oi' radial blading disposed in said passage. and at least one row of fan blading carried by each of said members and extending radially outwardly beyond the outer member, and a blade ring additional tothe blading in said passage carried by one of said members, said radial blading of said members being of such' form and pitch that they may be interthreaded for assembly.

17. Apparatus of the character specified comprising contrarotational members one within the other and carrying rows of radial blading between them and fan blading extending radially outwardly beyond said members, internal bearings for rotatably supporting said members. and a blade ring additional to one of said members,

said radial blading oi said members being o! such l form and pitch that they may be interthreaded for assembly.

18. Apparatus of the character specified co prising relatively rotatable inner and outer members spaced apart radially to form a passage between them and carrying rows of radial blading disposed in said passage, shafts for rotatably supporting said members, and a blade ring additional to and connecting one end only of at least one of said members to its shaft. the blading of saidl members being of such form and pitch that they may be interthreaded for assembly.

JOSEPH STANLEY VHALLl REFERENCES CITED The following references are of record in the lle of this patent:

UNITED STATES PATENTS Number Name Date 1,016,080 McCulloch Jan. 30, 1912 1,307,864 Jones June 24, 1919 2,004,571 Bothezat June 11, 1935 2,201,099 Roe May 14, 1940 2,276,695 Lavarello ---s Mar. 17, 1942 FOREIGN PATENTS Number Country Date 78,251 Sweden Sept. 5, 1933 

